yeah, its only suggested because the RPMS are no longer made..
also you really need to add at least .5 inches of rear drop to any spring thats originally made for the reg 6.. because the MS6 has another 300 lbs of drive train in the rear end.. so in effect the drop will be 1.5 all around... ive had 5 sets of springs on my MS6.. the tein Htechs for the V6 were easily the best for street driving.. if you want any kind race setup, coilovers are needed.. springs just tease this car!!